Magnetic switch



Nov. 10; 1970 V.G.MATTO ETAL 3,539,951

MAGNETIC SWITCH Filed Aug. 9', 1968 2 Sheets-Sheet 1 no m0 ALARM Q INVENTOR VICTOR G. MKIT7 O BY SANDOR A. VERES t 4 i Q Li 2 ATTORNEY Nov. 10, 1970 v. a. MATTO E1 3,539,957 I I MAGNETIC SWITCH Filed Aug. 9; 1968 2 Sheets-Sheet 2 INVENTORS VICTOR G. MHTTO BY SHNDOI? A- VE'RES ATTORNEY States Patent US. Cl. 335-405 8 Claims ABSTRACT OF THE DISCLOSURE A magnetic switch which includes two magnetic pole pieces spaced apart with an air gap between them and secured to a housing by means of conductive fasteners which are accessible outside the housing. A spring member is provided in the housing and carrying a magnetic plate for bridging the gap between the pole pieces and to complete a circuit between them. An external push button member is provided to perform an auxiliary switchclosing operation, and an auxiliary pole piece may be provided to form an auxiliary electrical circuit with the spring member and one of the pole pieces.

BACKGROUND OF THE INVENTION and is relatively simple in construction.

" p DESCRIPTION OF THE DRAWING I In the drawing:

FIG. 1 is a. sectional view of a switch embodying the invention;

FIG. 2 is a side view, partly in section, of the switch of FIG. 1; and

FIG. 3 is a sectional view of a modification of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A magnetic switch embodying the invention, referring to FIGS. 1 and 2, includes an insulating housing 20 in which are mounted two generally L-shaped metal pole pieces 30 and 40 made of a magnetic material. Pole piece 30 includes parallel horizontal arms 50 and 60 and a connecting vertical arm 70, and pole piece 40 includes parallel horizontal arms 80 and 90 and a connecting vertical arm 100. The two pieces 30 and 40* are oriented facing each other more or less as mirror images as shown, with a gap 110 between their corresponding arms 60 and 90 which are aligned and lie in the same horizontal plane. The two arms 50 and 80 are also aligned in the same horizontal plane and are used to secure the pole pieces in place in housing 20 by means of screw-type fasteners 120 and 130 which are passed through the housing and are secured to the pole pieces. The fasteners are also used as electrical terminals and are connected to an alarm circuit 132 of any suitable type. Vertical arms 70 and 100 of the pole pieces 30 and 40 are parallel to each other as shown.

A flexible leaf spring 140, which is generally L-shaped and includes a short arm 150, a relatively elongated arm 160, and a connecting portion 170 between them, lies inside pole piece 30 and has its short arm 150 secured to the arm 50 of the pole piece by fastener 120, and it is so shaped that the connecting portion 170 lies adjacent to the vertical wall 70 of the pole piece 30, and the elongated arm 160 extends more or less parallel to the arm 60 across the gap 110, and the end 180 of arm 160 overlies a portion of the arm 90 of the second pole piece 40.

The end 180 of the elongated arm carries a contact member 190 which is generally conical in shape and is adapted to make contact with a corresponding button-like contact member 200 on the arm 60 of the pole piece 40. A plate 210 of magnetic material is also secured to the under side of the elongated arm 160 of the flexible spring 140. The plate 210 is thinner than the conical contact member 190 is high so that the conical contact member 190 can make contact with the button member 200, with the plate being out of contact with the pole pieces 30 and 40 and spaced therefrom by about a millimeter or less.

A push button operator 240 is provided in operative relation with the housing 20. The push button is slidably mounted on an extension 250 of the housing and carries a piston 260 slidably mounted in an opening 270 in the housing. The piston is secured to the push button and has a general conical tip 280 which has a locking lip 290 for engaging a tab 300 on leaf spring 140. The piston also includes a second lip 310 which is adapted to engage a notch 320 in the wall portion of the housing and to limit travel of the piston and push button in a direction out of the housing. The piston carries a helical spring 330 in side the push button 240 which is compressed when the push button and piston are moved toward housing 20 and which tends to urge the push button and piston away from housing 20.

In operation of the switch shown in FIGS. 1 and 2, the push button is operated to push the piston into locking engagement with the tab on the leaf spring. This operation closes the contacts 190 and 200 but does not bring the plate210 into engagement with the pole pieces. This, in effect, sets the switch. Then when an auxiliary member, for example a door 212, carrying a magnet 214 is closed with its magnet in operative'relation with the switch, it pulls the plate 210 into engagement with the pole pieces 50 and 60. The dimensions of the parts are such that this pulls spring 140 down enough to release the push button piston 260 from the tab 300, and the piston returns to its outer released position under the influence of spring 330 to be ready for a subsequent cycle of operation. The

switch, of course, remains closed. Now, if the door 212 is opened and the magnet 214 held thereby is removed from the magnetic switch, the leaf spring is released and retracts and opens the electrical circuit and causes an alarm to sound.

A modified switch 10" which has somewhat greater flexibility than switch 10 includes all of the elements of switch 10 except the push button assembly 240 and locking tab 300 on leaf spring 140. Switch 10' includes an auxiliary metal pole piece 340 of nonmagnetic material secured in the housing by a screw fastener 350 similar to fasteners and and accessible on the same surface of the switch housing as these fasteners. The pole piece 340 includes an arm 360 which has its end positioned adjacent to the end of leaf spring 140. The top surface of the spring carries a contact 370 which is adapted to engage a similar contact 380 on pole piece 340.

Switch 10' is a double-acting switch since one circuit is completed or opened through contacts 370 and 380 when the leaf spring 140 is in its elevated position, and a second circuit is completed through contacts and 200 when the leaf spring is pulled down to its second position as described above.

What is claimed is:

1. A magnetic switch comprising an insulating housing having large-area top and bottom walls and relatively narrow first and second side walls,

a first generally U-shaped member of magnetic material seated in said housing in a snug fit and having a first arm in contact with said top Wall, a second arm in contact with said first side wall and a third arm in contact with said bottom wall,

a second generally U-shaped member of magnetic material seated in said housing in a snug fit facing but spaced from said first U-shaped member and including a first arm in contact with said top wall, a second arm in contact with said side wall and a third arm in contact with said bottom wall,

said third arm of said first U-shaped member being coplanar with but spaced from said third arm of said second U-shaped member,

a first screw terminal securing said first arm of said first U-shaped member to said top wall and a second screw terminal securing said first arm of said second U-shaped member to said top wall,

said first and second screw terminals having screw attaching portions positioned outside said housing and accessible for making electrical connection thereto, and

a U-shaped, resilient spring-like contact member positioned inside said housing and having a first portion secured to said second screw terminal, and a second portion extending along but spaced from said second side wall, and a third portion extending along but spaced from said bottom wall, the spring-like natureof said contact member biasing said third portion away from and out of contact with said third arms of said first and second U-shaped members,

said third portion of said contact member having a surface which is positioned adjacent to and faces said third arms and carries a metallic magnetic plate,

said first and second U-shaped members being adapted,

to receive magnetic flux from an external magnet positioned anywhere near said housing to attract said magnetic plate on said resilient contact member whereby a circuit is closed between said third arms of said two members.

contact members being adapted to make contact before. 45

3. The switch defined in claim 1 wherein said movable said plate contacts said two metal members.

contact member is a resilient, flat spring and extends from 2. The switch defined in claiml and includingauxib.

said one of said fasteners and one of said metal members to near the other metal member across the gap between them.

4. The switch defined in claim 3 wherein one of said auxiliary contact members is secured to the end of said fiat spring adjacent to said other metal member and the other auxiliary contact member is secured to said other metal member.

5. The switch defined in claim 1 and including a springbiased push button having a slidable piston,

a tab on said movable contact member adapted to engage and lock said slidable piston in switch-closing position, in which position said auxiliary contact members make contact,

the closure of said magnetic plate across said gap and into engagement with said two metal members under the influence of an external magnet serving to release said piston from said tab whereby said piston and said push button return to their normal ready position.

6. The switch defined in claim 1 and including an auxiliary magnetic metal member secured on said housing by means of a metal fastener, said auxiliary metal member being adapted to contact said movable contact member to provide an auxiliary alarm circuit.

7. The switch defined in claim 1 wherein said metal members are generally L-shaped and include first, second, and third arms shaped to formthe L, the first and third arms of said members being aligned in respective parallel planes, said second arms being spaced apart parallel to each other with said-insulating gap being present between said first arms of said members.

r 8. The switch defined in claim 1 and including .a third contact plate in said housing, said spring-like contact member normally making electrical contact with said third contact plate, said electrical contact being broken when said contact member and its magnetic plate make contact with said pair of metal members.

, References Cited UNITED STATES PATENTS 3,273,090 9/1966 Malin 335-205 BERNARD A. GILHEANY, Primary Examiner R. N. ENVALL, JR., Assistant Examiner 

